[The regulation of retinoid X receptor-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury].

The aim of this study was to investigate the regulatory role of retinoid X receptor (RXR)-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury (PIRI) and the underlying mechanism. Seventy-seven male Sprague-Dawley (SD) rats were randomly divided into 7 groups (n = 11): control group, sham group, sham+9-cis-retinoid acid (9-cRA, RXR agonist) group, sham+HX531 (RXR inhibitor) group, ischemia/reperfusion (I/R) group, I/R+9-cRA group, and I/R+HX531 group. The unilateral lung I/R model was established by obstruction of left lung hilus for 30 min and reperfusion for 180 min in vivo. The rats in I/R+9-cRA and I/R+HX531 groups were given intraperitoneal injection of 9-cRA and HX531 before thoracotomy. After reperfusion, the left lung tissue was taken to evaluate the lung tissue injury, and the oxidative stress-related indexes of the lung tissue were detected by the corresponding kits. The lung tissue morphology and the ultrastructure of the alveolar epithelial cells were observed by HE staining and transmission electron microscope, respectively. The protein expression of RXR in lung tissue was observed by immunofluorescence labeling method, and the expression level of nuclear factor E2-related factor (Nrf2) protein was detected by Western blot. The results showed that, compared with the sham group, the I/R group exhibited obviously injured lung tissue, decreased SOD activity, increased MDA content and MPO activity, and down-regulated expression level of Nrf2 protein. Compared with the I/R group, the I/R+9-cRA group showed alleviated lung tissue injury, increased activity of SOD, decreased MDA content and MPO activity, and up-regulated expression levels of RXR and Nrf2 protein. The above-mentioned improvement effects of 9-cRA were reversed by HX531 treatment. These results suggest that RXR activation can effectively protect the lung tissue against I/R injury, and the mechanism may involve the activation of Nrf2 signaling pathway, the enhancement of antioxidant level and the reduction of oxidative stress response.

[Effects of excessive endoplasmic reticulum stress on lung ischemia/reperfusion induced myocardial injury in mice].

OBJECTIVE: To investigate the effects of excessive endoplasmic reticulum stress on lung ischemia/reperfusion (I/R) induced myocardial injury in mice. METHODS: Forty healthy SPF male C57BL/6J mice were divided into 4 groups randomly (n=10):sham operation group (Sham group), lung I/R group (I/R group), endoplasmic reticulum stress (ERS) pathway agonist Tunicamycin group (TM) and ERS inhibitor 4-phenyl butyric acid group (4-PBA). The model of lung I/R injury was established by clamping the left hilum of lung for 30 min followed by 180 min of reperfusion. In sham group, only sternotomy was performed, the hilum of lung was not clamped, and the mice were mechanically ventilated for 210 min. In TM and 4-PBA groups, TM 1mg/kg and 4-PBA 400 mg/kg were injected intraperitoneally, respectively, at 30 min before establishment of the model. At 180 min of reperfusion, blood samples were collected from the orbit for determination of myocardial enzyme. The animals were then sacrificed, and hearts were removed for determination of light microscope, TUNEL, Caspase 3 enzymatic activity, real-time polymerase chain reaction and Western blot. RESULTS: Compared with sham group, the cardiomyocytes had obvious damage under light microscope, and the serum creatine kinase-MB (CK-MB) and lactic dehydrogenase (LDH) activities, apoptosis index and Caspase 3 enzymatic activity were increased significantly, the expressions of p-Jun N-terminalkinase(p-JNK), Caspase 12, CCAAT/enhancer-binding protein homologous protein (CHOP) and glucose regulated protein 78(GRP78) protein and mRNA were up-regulated in I/R, TM and 4-PBA groups (P<0.01). Compared with I/R group, the cardiomyocytes damage was obvious under light microscope, and the serum CK-MB and LDH activities, apoptosis index and Caspase 3 enzymatic activity were increased significantly, the expressions of p-JNK, Caspase 12, CHOP and GRP78 protein and mRNA were up-regulated in group TM; while all above changes were relieved in group 4-PBA (P<0.01). Compared with TM group, the cardiomyocytes damage was relieved under light microscope, and the serum CK-MB and LDH activities, apoptosis index and Caspase 3 enzymatic activity were decreased significantly, the expressions of p-JNK, Caspase 12,CHOP and GRP78 protein and mRNA were down-regulated in group 4-PBA. CONCLUSIONS: The excessive endoplasmic reticulum stress participates in myocardial injury induced by lung ischemia/reperfusion (I/R) and inhibit excessive endoplasmic reticulum stress response can relieved myocardial injury.

[Effect of dexmedetomidine on apoptosis and CHOP in hypoxia/reoxygenation injury A549 cell].

OBJECTIVES: To investigate the effects of dexmedetomidine (Dex) on injury of A549 cells induced by hypoxia/reoxygenation(H/R)and the influence of C/EBP homologous protein (CHOP) expression. METHODS: Logarithmic growth phase A549 cells(it originated from alveolar type Ⅱ epithelial cell line) were randomly divided into 4 groups (n=10):normoxic control group (N), Dex group (D), hypoxia/reoxygenation group (H), hypoxia/reoxygenation + Dex group(HD). At the beginning of modeling, 1 nmol/L Dex was puted into D and HD groups. N and D groups were cultured in the normoxic incubator for 30 h. H and HD group were incubated in the anoxic cultivation for 6 h, fo llowed by normoxic culture for 24 h. Then A549 cells were observed under the inverted microscope to observe the morphological changes. Cell activity was detected by cell counting Kit-8(CCK-8) and the apoptosis index(AI) was detected by in situ end labeling (TUNEL) method. The expression of CHOP、glucose-regulated protein of molecular weight 78 kDa (Grp78)、cysteinyl aspirate-specificprotease-3 (caspase-3) protein and CHOP、Grp78 mRNA were detected by Western blot and RT-PCR. RESULTS: Compared with N group, the number of adherent cells in H group decreased significantly, and cell morphology changed. The absorbance value in H group decreased obviously (P<0. 01). The AI value and expression of CHOP, Grp78, caspase-3 proteins and CHOP, Grp78 mRNA were significantly increased (P<0.01). Compared with H group, the cell damage in HD group was decreased, the absorbance value increased (P<0.01), the number of apoptosis cells decreased relatively (P<0.01), the expression of CHOP, caspase-3 protein and CHOP mRNA decreased (P<0. 01). CONCLUSIONS: Dex has notable effects against H/R injury, which may be related to effective inhibition of apoptosis mediated by the CHOP's signal path.

[Excessive endoplasmic reticulum stress mediates brain damage in hypoxia hypercapnia induced pulmonary hypertension rats].

The purpose of the present study was to investigate the effect of excessive endoplasmic reticulum stress (ERS) on the brain damage in hypoxia hypercapnia induced pulmonary hypertension (HHPH) rats. Forty healthy SPF male SD rats were randomly divided into four groups (n = 10 for each): control group, hypoxia hypercapnia group, ERS pathway agonist tunicamycin (TM) group and ERS pathway inhibitor 4-phenylbutyric acid (4-PBA) group. The rats of control group lived in normal environment, while the rats of other three groups were raised for four weeks in the tank with 8.5%-11% O2 and 5%-6% CO2. TM (0.08 mg/kg, twice a week) and 4-PBA (80 mg/kg, daily) were respectively intraperitoneally injected into the rats of TM and 4-PBA groups, and the hypoxia hypercapnia group was given the same volume of normal saline. The mean pulmonary artery pressure and heart perfusion of the rats were determined and recorded after four-week raising. Then the brain tissue of the rats were quickly taken out for the brain water content measuring and morphological changes observing. The Caspase-3 activity and the apoptotic index of the brain cells were also determined. The protein and mRNA expressions of p-JNK, Caspase-12, CHOP and GRP78 in brain tissues were detected by Western blot and RT-PCR. The results showed that compared with the control group, the mean pulmonary artery pressure, brain water content and brain cells apoptotic index, Caspase-3 activity, the protein and mRNA levels of p-JNK, Caspase-12, CHOP and GRP78 were increased (P < 0.05), and the brain tissues of the rats were obviously damaged in the rats raised in the hypoxia hypercapnia environment; compared with hypoxia hypercapnia group, the mean pulmonary artery pressure, brain water content, brain apoptotic index and Caspase-3 activity, p-JNK, Caspase-12, CHOP, GRP78 protein and mRNA expressions in TM group were increased (P < 0.05), and the brain tissues of the rats were obviously damaged, while all above changes were relieved in 4-PBA group (P < 0.05). These results suggest that excessive ERS may participate in the brain injury induced by HHPH in rats and inhibition of excessive ERS can relieve the brain injury in the rats with HHPH.

[Effects of dexmedetomidine on hypoxia/reoxygenation injury-induced cell apoptosis and caspase-12 expression in A549 cells].

To investigate the effects of dexmedetomidine (DEX) on hypoxia/reoxygenation (H/R) injury-induced cell apoptosis and caspase-12 expression, A549 cells were randomly divided into 4 groups: control group, DEX group, H/R group and DEX+H/R group. Cells of control and DEX groups were cultured in the normoxic incubator for 30 h. Cells of H/R and DEX+ H/R groups were incubated in the anoxic cultivation for 6 h, followed by normoxic culture for 24 h, and DEX (1 nmol/L) was added into the culture medium in DEX and DEX+H/R groups. Morphological changes were observed under the inverted microscope. Cell viability was detected by CCK-8. The apoptosis index (AI) of A549 cells was detected by TUNEL method. The activity of caspase-3 enzyme in cells was detected by using caspase-3 kit. The expressions of GRP78, caspase-12 protein and mRNA were determined by Western blot and RT-PCR respectively. Compared with control group, the morphological changes of the cultured cells were observed: some of the cell fusion occurred and the shape of the cells was multilateral; the cell viability was decreased significantly (P < 0.01), the number of apoptotic cells and the AI value, caspase-3 activity, and the expressions of GRP78, caspase-12 protein/mRNA were significantly increased (P < 0.01) in H/R group. While the administration of DEX alleviated the H/R injury-induced cell damage, obviously increased the cell viability (P < 0.01), significantly decreased the increment of apoptotic cells and the AI value induced by H/R injury (P < 0.01), and also dramatically decreased the H/R injury-induced high level of caspase-3 activity (P < 0.01) as well as high expression of caspase-12 protein and mRNA (P < 0.01). Taken together, the results suggest that DEX can effectively protect A549 cells from the H/R injury, which may be mediated by down-regulating the expression of caspase-12 and inhibiting cell apoptosis.

[Effects of Dexmedetomidine on the levels of proinflammatory mediators IL-1ßand TNF-α in pulmonary ischemia/reperfusion injury rats and the mechanisms].

OBJECTIVE: To evaluate the effects and mechanism of the Dexmedetomidine on the levels of proinflammatory mediators interleukin 1 beta (IL-1ß) and tumor necrosis factor-α(TNF-α) in ischemia/reperfusion(I/R)rats. METHODS: Fifty healthy SPF male SD rats, 250~310 g,8~12 weeks,were randomly divided into five groups(n=10):sham operation group(sham group),I/R group, dexmedetomidine group(Dex group), atipamezole group(Atip group), dexmedetomidine plus atipamezole(Dex+Atip group). The I/R model was established by clipping hilus of left lung for 30 min and then reperfusion for 2 h. Dex group, Atip group and Dex + Atip group were performed by intraperitoneal injection dexmedetomidine(20 µg/kg),atipamezole(250 µg/kg),Dexmedetomidine(20 µg/kg)+atipamezole(250 µg/kg)respectively 30 min in advance before hilus of left lung was clipped, the rest of the process was the same with I/R group. After the experiment the rats were killed and the left lung tissues to determine the lung wet/dry weight(W/D) and total lung water content(TLW); Ultra structure of lung tissues were observed under light microscope and electron microscope; IL-1ß and TNF-α levels were determined by using ELISA. RESULTS: Compared with the sham group, the W/D、TLW、IL-1ß and TNF-α in other groups were increased significantly (P<0.05). The structure damages of lung tissues observed under light microscope and electron microscope in other groups were more serious than that of sham group. Compared with I/R、Atip、Dex+Atip group, the levels of W/D、TLW,IL-1ß and TNF-α in Dex group were lower (P<0.05), the structure damages of lung tissues observed under light microscopy and electron microscope in Dex group were slighter. There was no significant difference of the above parameters among I/R、Atip、Dex+Atip group. CONCLUSIONS: Dexmedetomidine can alleviate ischemia/reperfusion injury in rat lung through lowering the level of proinflammatory mediators IL-1ß and TNF-α,the possible mechanism may be through stimulation of α2 adrenaline receptors.

[Effect of dexmedetomidine on renal injury induced by lung ischemia/reperfusion in mice].

OBJECTIVE: To evaluate the effect of dexmedetomidine(Dex) on renal injury induced by lung ischemia/reperfusion(I/R) in mice. METHODS: Fifty healthy SPF male C57BL/6J mice, weighing 20 g~24 g,aged 8~10 weeks,were randomly divided into five groups(n=10 each):sham operation group(sham group),lung ischemia/reperfusion group(I/R group), lung ischemia/reperfusion and normal saline group (NS group), dexmedetomidine group(Dex group), dexmedetomidine and atipamezole group (DA group). Lung ischemia/reperfusion model was established by occlusion of the left pulmonary artery for 30 min followed by 180 min reperfusion in mice. In Dex and DA groups, dexmedetomidine 20 µg/kg and dexmedetomidine 20 µg/kg plus atipamezole 250 µg/kg were injected intraperitoneally respectively at 30 min before establishment of the model, isopyknic normal saline instead of Dex were injected intraperitoneally in NS group. After the experiment the mice were killed and plasma IL-1 beta and tumor necrosis factor α(TNF-α) concentration were detected by ELISA; the renal tissues were harvested to observe ultra structure under electron microscope. RESULTS: Compared with sham group, the concentrations of IL-1ß and TNF-α in other groups were increased significantly and the structure damages of renal tissues observed under electron microscope in other groups were more serious than those of sham group. Compared with I/R group, NS groups and DA group, the concentrations of IL-1ß and TNF-α in Dex group were significantly lower(P<0.05)and the structure damages of renal tissues observed under electron microscope in Dex group were slighter. CONCLUSIONS: Dexmedetomidine pretreatment can attenuate renal injury induced by lung ischemia/reperfusion and the mechanism may be related to inhibition of inflammatory responses.

[The effects of YHTJF on lung ischemia/reperfusion injury in mice].

OBJECTIVE: To explore whether yiqi huoxue tongluo jiedu fang (YHTJF, Traditional Chinese Medicine) alleviates the injury during lung ischemia/reperfusion (I/R) in mice through inhibiting oxidative stress or not. METHODS: C57BL/6J male mice (n=70) were randomly divided into 7 groups:control (C), carboxyl methyl cellulose-Na(CMC·Na) + normal control (CC), carboxyl methyl cellulose-Na + sham (CS), carboxyl methyl cellulose-Na + I/R (CIR), carboxyl methyl cellulose-Na + YHTJF-Low, CMC-Na + YHTJF-Middle, CMC-Na + YHTJF-High (CYL, CYM, CYH). The mice in CYL, CYM and CYH group were treated with YHTJF by intraperitoneal injection every day, while the carboxyl methyl cellulose-Na was administered with the same volume of CYL in CC, CS and CIR group. After 3 h-reperfusion, the left lung tissues were harvested to determine the lung wet/dry weight (W/D), the total lung water content (TLW), and the index of quantita-tive evaluation for alveolar damage (IQA). Morphological observation and terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) were applied to evaluate the structural changes and the apoptosis index (AI) of the lung tissues. The expressions superoxide of dis-mutase(SOD), malondialdehyde(MDA) and myeloperoxidase(MPO) in the lung tissues were detected by kits. RESULTS: Compared with group C, the W/D, TLW, IQA, AI, lung tissue structural changes, and the expressions of MDA and MPO in group I/R were increased obviously (P < 0.01), and the expression of SOD was decreased, while there was no significant difference between group CC and CS. Compared with group I/R, the parameters of these experiments in group CYL, CYM, CYH were all decreased, and the expression of SOD was increased, while the reduction in group CYM was the most remarkable among them (P < 0.01). CONCLUSIONS: YHTJF may attenuate the I/R injury of the lung by the inhibition of apoptosis via ROS pathway.

[Effects of xuebijing injection on cardiac function and structure in rats with myocardial hypoxia/reoxygenation injury].

OBJECTIVE: To investigate the protective effects of xuebijing (XBJ, Traditional Chinese Medicine Complex) injection on cardiac function in rats with myocardial hypoxia/reoxygenation(H/R) injury. METHODS: The isolated langendorff perfused rat heart model was established. One hundred and thirty SD rats were randomly divided into sham group, hypoxia/reoxygenation group, low dose XBJ(XBJL) group, middle dose XBJ(XBJM) group and high dose XBJ(XBJH) group. All groups except sham group were divided into three subgroups according to reoxygenation time(0.5 h,1 h, 2 h) (n=10). In sham group, left ventricular development pressure(LVDP), maximal rates of increase/decrease of the left ventricular pressure(±dp/dtmax), left ventricular pressure (LVP), and heart rates (HR) were recorded after 20 minutes balance perfusion. The creatine kinase-MB (CK-MB) in myocardium was detected by ELISA. In other groups, after 20 minutes balance perfusion, we perfused ThomasⅡto stop the hearts from beating for 30 minutes, then reperfused the K-H until hearts recover beating. The microstructure of myocardium was observed under light microscopy. LVDP, ±dp/dtmax, LVP and HR were continuously recorded in other four groups and the concentrations of CK-MB in myocardium were measured by ELISA at different time points after reoxygenation. Microstructure of myocardium in each group were observed under light microscopy. RESULTS: LVDP, ±dp/dtmax, LVP and HR of other groups were significantly lower than those of sham group(P<0.05). The levels of CK-MB were higher than that of sham group(P<0.05). LVDP, ±dp/dtmax, LVP and HR of XBJL, XBJM and XBJH groups were higher than those of I/R group at corresponding time points after reoxygenation(P<0.05). The levels of CK-MB were lower than that of I/R group(P<0.05) and the cardiac function was improved. The middle dose of XBJ had the best protective effect. CONCLUSIONS: Xuebijing injection can effectively improve cardiac function and structure in rats with myocardial hypoxia/reoxygenation injury, and middle dose of XBJ is the best.

[Effect of dexmedetomidine on expression of endoplasmic reticulum stress-related Caspase-12 in lung ischemia/reperfusion injury mice].

OBJECTIVE: To investigate the effect of dexmedetomidine (DEX) on expression of endoplasmic reticulum stress (ERS)-related cysteinyl aspirate specific proteinase-12 (Caspase-12) in lung ischemia/reperfusion (I/R) injury mice. METHODS: Forty C57BL/6J mice were randomly divided into 4 groups:sham operation group (sham group),ischemia/reperfusion injury group (I/R group), normal salinecontrol group (NS group), ischemia/reperfusion + dexmedetomidine group (DEX group). Dexmedetomidine was infused intraperitoneally into the mice to stablish situ left pulmonary I/R injury mouse model. In NS group, the isometric dexmedetomidine was replaced by normal saline,other operations were as the same as the DEX group. After reperfusion 3 hours, the lung tissue wet/dry weight (W/D), the total lung water content (TLW) of the left lung tissues were determined. The lung tissue morphology changes were observed by light microscopy and the damage assessment(IQA) was taken. The structure changes and the apoptosis index (AI) of the lung tissues were evaluated by TUNEL method. The protein and mRNA expression of Caspase-12 and grp78 in lung tissues were detected by Western blot and reverse translate-PCR. RESULTS: Compared with the sham group, the W/D, TLW, IQA, AI, lung tissue structure damages, and the expression of Caspase-12 and grp78 protein and mRNA obviously raised both in I/R group and NS group (P<0.01 or P<0.05). Compared with I/R group, the W/D, TLW, IQA, AI of DEX group were all decreased, the demaged lung tissue morphology changes were significantly reduced, the protein and mRNA expression level of Caspase-12 and grp78 in DEX group were decreased (P<0.01). CONCLUSIONS: DEX can effectively relieve the lung I/R injuries in mice, which maybe associated with inhibition of pneumocyte apoptosis induced by ERS-related Caspase-12 pathway.